Electromagnetically-operated device



H. R. CANF IELD. ELECTROMAGNETICALLY OPERATED DEViCE.

. APPLICATION FILED FEB. 16, I917- RENEWED HAY HHHZO- 001;. 5, 1920. 2 ShEETS-SHEET 1 0 H R. CANFIELD.

ELEGIROMAGNETICALLY OPERATED DEVICE. APPLLCAIIONYHLED FEE. I6, 1911. RENEWED HAY 11.1920.

1,354,882. Patented M 5,1920.

2 SHEETS-SHEET 2- IN VENTOR.

A TTORNE Y.

UNITED STATES PATENT OFFICE.

HARRY R. CANFIELD, 0F CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC CON- TROLLER & MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A CORPORA- TIOIN OF OHIO.

ELECTROMAGNETIOALILY-OPERATED DEVICE.

Application filed February 16, 1817, Serial No. 149,003.

T 0 all whom it may concern:

Be it known that I, HARRY R. OANFIELD. a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Electromagnetically-Operated Devices, of which the following is a specification.

This invention relates to magnetically operated devices, and particularly to magnetically operated switches.

It is one of the objects of my invention to provide an electromagnetic switch which, when its operating winding is energized above a predeterminec value, remains in its normal or open position without restraint due to magnetism produced by the winding, and which closes when the energization of the winding falls to a predetermined value and thereafter remains closed without the assistance of the winding. The switch has mechanical bias both to the open and to the closed position, and the function of the mag netic circuit and its energizing winding is to permit the bias which holds the switch open to act when the winding is energized above a predetermined value, and to bring into action the bias which causes the switch to close and which holds it closed when the energization of the winding is below or is lowered to a point below the predetermined value.

In the drawings, Figures 1, 2, 3, and 4 show side views, partly in section and partly broken away, of three of the many forms in which my invention may be embodied.

Referring to Fig. 1 of the drawings, the energizing winding is shown at 1. The magnetic circuit energized by the winding 1 has the vertically movable core or plunger 2, the stationary main frame composed of the right branch 3 and the left branch 4, the

armature '5 pivoted at 6, and the stationary pole piece 7. The plunger 2, preferably enlarged at its lower end to increase its weight, is suspended in position by a nonmagnetic stem 9, rigidly connected thereto and having at its upper end a head 10 resting upon the finger 11 of the main switch arm 19 to be described. The right branch 3 of the magnetic circuit is preferably restricted in cross section, and is surrounded by a choke sleeve 12 preferably of copper or other material having low electrical resist- Specification of Letters Patent.

Renewed May 17, 1920. Serial No. 382,083.

end of the armature 5; an air gap 14 between the upper end of the branch 3 and the armature 5; an air gap 15 between the pole piece 7 and the left-hand end of the armature 5; an air gap 15 between the upper end of the left branch 4 and the armature 5; and an air gap 16 between the upper end of the plunger 2 and the pole piece 7. The gaps 14, 14 may be diminished, and the gaps 15, 15 increased, or vice versa, by means of the non-magnetic adjusting screw 83, whose adjustment may be fixed by the lock nut 34. The armature 5 is normally biased to rotate in a counter clockwise direction, and is stopped by the non-magnetic screw 33 abutting on the pole piece 7.

lVhen the winding 1 is energized, flux generated thereby flows, say upwardly, in the plunger 2 across the air gap 16 into the pole piece 7, tending to lift the plunger: there the flux divides, part going to the right across the gap 14 into the armature 5, back across the gap 14 tending to rotate the armature 5 in the clockwise direction, and thence by way of the branch 3 back to the plunger 2; the other portion of the flux flows to the left across the gap 15 to the left-hand end of the plunger 5 and across the gap 15, augmenting the normal bias and tending to rotate the armature 5 in the counter clockwise direction, and thence by way of the branch 4 back to the plunger 2.

The bracket 17, which carries the pivot 6 of the armature 5, also carries a pivot 18 upon which is mounted the main switch arm 19, carrying the switch contact 20. A spring 21 presses on the switch arm 19 at 22, along a line of action slightly above the center of the pivot 18, tending to rotate the switch arm 19 in clockwise direction. The movement in this direction is limited by the stop 23 on the bracket 17. The finger 11, before mentionech'is integral with the switch arm 19, and has the hole 24 through which the plunger stem 9 passes. When the parts are in the normal, that is, the deenergized, position shown, the weight of the plunger 2 'supported by the head on the finger 11 assists the spring 21 to exert a clockwise torque to hold theswitch-arm 19in its open position the bracket. Another stop 32 on the bracket is provided to limit the counter-clockwise movement of the arm 26 when the contact engaged by the contact 20, as will be described.

The operation of my invention is as follows; When the winding is energized with current below'a predetermined value, the magnetic flux in the gap 16 lifts the plunger 2 andcarries it up into engagement with the pole piece 7. This removes the weight of the plunger from the finger 11, the switcharm 19 thereafter being held in open 'posi tion by the spring 21 only. The magnetic flux in the gaps 14 and 14 overpowers the flux in the gaps 15 and 15 and the armature 5 is rotated clockwise about the pivot 6, closing the gaps 14, 14; This movement causes a peen 35 on the armature to engage the finger 11 of the switch arm at 36 and to rotate the switch arm 19 counter-clockwise sufficiently to bring the center line of action of the compression spring 21 below the center of the pivot 18. The spring 21 then continues the rotation of the arm 19 and brings the contact 20 into engagement with the contact 25, the contact 25 retreating and compressing thespring 29, securely sealing the contacts with a wiping action.

The movement of the contacts is finally limited by the finger 31 striking the stop 32.

Bymaking electrical connections to the studs 3'? and 38, which are connected respectively with the brackets 17 and 28, the closure of the contacts 20 and 25 may be employed to close an electric circuit.

When, however, the winding 1 is energized with current, above the said predetermined value, the plunger 2 is not only raised,

7 but suflicient flux is generated to satisfy the magnetic capacity of the restricted branch 3,

and a greater proportion of the total flux flows in the left branch 4 and exerts suf:

. ficient magnetic pull across the gaps 15, 15

to hold the armature 5 against the opposing magnetic pull in thegaps 14 and 14 The choking sleeve 12 on the restricted branch 3 insures against the predominance of pull in the gaps 14 and 14 during the interval in which the flux is building up to full strength, by .momentarily choking the flux out ct therestricted branch 3.

Upon a reduction of current in the wind-- the flux in the gaps 15 and15 'fal1s more rapidly than that in the gaps 14 and 14 and the pull in the gaps 14 and 14 over- 7 powers that in the gaps 15 and 15", whereupon the armature 5 is rotated clockwise and the switch contacts are closed as above described.

After the contacts have closed they remain closed as long as the plunger 2 is held up.- If the winding 1 be deenergized, or its energization reduced to a predetermined mini mum, the armature 5 will return to its normal position, as shown, and the plunger 2 will fall, causing the head 10 to strike the finger 11 and rotate the switch arm 19 clockwise against the stop 23, thusopening the switch contacts.

The aforesaid predetermined value may be adjusted by. adjusting the relative sizes of the air gaps 14, 14 and 15, 15*, by means of the screw In the form of my invention shown in i i Fig. 2, the magnetic circuit energized by the winding 40 has the main frame 42, stationary pole piece 43 supported in the main frame by the shoulder 43?, the plunger .44, the plunger tail piece 45 integral therewith and of restricted cross section, and the magnetic sleeve 46 threaded into the frame 42 at 4'7 and adjustable axially therein. The tail piece 45 carries a non-magnetic sleeve 48 to prevent its sticking to the sleeve 46 when magnetically energized. The axial position of the sleeve may be fixed by the lock nut 49. Two gaps are thus provided, the gap 50 hetween the pole piece 43 and the armature 44, and the gap 51 between the armature 44 and the adjustable sleeve 46. The armature 44 is suspended in position by the non-magnetic stem 52 rigidly secured thereto and passing upwardly through the pole piece 43, and having the head 53 resting on the pole piece. The stem is continued above the head'53, passing through a perforation 55 in the finger 56 of the main switch arm 57 and terminating in a head 54.

vi hen the winding is energized, theflux flows, say upwardly, in the armature 44, across the gap 50 into the pole 1 169. 43, and. ,hrough the main frame 42 to the lower part thereof; there the flux divides, part taking a path upwardly through the sleeve 46 across the gap 51, into the armature 44, and part going directly into the tail piece 45 and thence into the armature 44.

Themain switch arm 57 is pivoted at 58 to a supporting bracket 59. A. spring- 60 presses on the switch arm at 61 along a line of action slightly above the center of the pivot 58, giving to the switch arm 57 a clockwise torque holding it against the stop 62 on the bracket. Another stop 63, on the bracket likewise limits the counter clockwise mow:- ment of the arm. The upper end of the switch arm 57 carries the contact plate 64 which co-acts with the stationary contact 65, mounted on the supporting bracket 66.

The operation of the form of my invention shown in 2 is as follows: W hen the winding 40 is energized'with current below a predetermined value, the magnetic pull in the gap 56 predominates over that in the gap 53, and the armature 44 is lifted, carrying upward the stem 52 and the head 53, and causing the latter to engage the iinger and rotate the switch arm 5? counterclo.;kwise suiliciently to cause the line of action of the spring 60 to lie below the center of the pivot 58. The spring 60 then rotates the arm 57 counter-clockwise, bringing the contact 64 into engagement with the contact 65, this movement being finally stopped by the stop \Vhen, however, the winding 40 is encrgized with current ab ve the predetermined value, the magnetic pull in the gap 51 predominates over that in the gap 50, and the armature 44 is held down. If th current now be reduced to a point below the -ained value, the pull in the gap 50 will again predominate over that in the gap 51., and the armature 44 wi l he lifted, and the switch will be closed as above described. ifter the switch has closed it will remain .ed as lone the armature 44 is held v. When the winding 40 is de'e'ner ized, or its energization reduced to a pre etermin d minimum, the plunger 44 will fall and the head 54 will strike the finger 50 and rotate the switch arm 57 clockwise until the line of action of the sprin 6O lies above the center of the pivot 58, whereupon the spring will continue the clockwise movement of the arm, the extent of the movement being limited by the stop 62. The switch contacts are thus opened. If oesired, the switch arm may be held in open position by the spring 60 alone, th weight of the armature 4 and its moving system being supported by the head 53 on the pole piece 43 shown, a small clearance being allowed for this purpose at 67, between the head 54 and the finger 56, when the parts are in the position shown.

la the form of my i vent-ion shown in V, 3, the magnetic circ it is a modification of, that shown in Fig. 1. and has the left branch 72, the pole piece Y3 and the weighted plunger 74, energized by the winding 71. The armature '79, pivotec at '?6, is overbalanccd by the weight 77, tending to rotate it clockwise; and in the normal position, the clockwise rotation of the armature opped y the peen 35 the under of t switch arm finger 11 at 36. The

pl. T4 is suspended in position by its non-i. gnetic stem 9. and the head 10, upon the nnger 11, as in Fig. l, and when in the normal position shown, its welght prevents the overbalanced armature from rotating the finger 11. A sin le non-magnetic spacer T5 is used and thus one pair of gaps is provided, the gap 78 between the left-hand end of the armature and the branch 72, and the gap '78 between the armature and the pole piece Theswitch arm and the con tact members are the same in all essentials as those shown in Fig. 2.

The operation of the form shown in Fig. 3 is as follows: When the winding 71 is energized with current below a predetermined value, the plunger 7 4 is lifted, removing the head 10 and hence the weight of the plunger 74 from the finger 11; the weight 77 then rotates the armature 79 clockwise, causing the peen 35 to lift the finger 11, giving to the switch arm 57 sufiicient counterclock wise movement to enable the spring 60 to close the switch contacts as described in connection with Fig. 2. When the winding 71 is energized with current above the predetermined value, the magnetism in the gaps 7 8 and 78 rotates the armature 7 9 counterclockwise until the non-magnetic adjusting screw 33 engages the pole piece 7 3, thus hold ing the peen 35 out of engagement with the arm 11. At the same time the plunger 74 is lifted. When the current is lowered below the predetermined value, the weight 77 overcomes the pull in the gaps 78 and 78 and rotates the armature clockwise, causing the peen 35 to engage the finger 11, initiating the movement of the arm 57, and causing the switch to close as above described. The contacts remain closed so long as the plunger is held up. YVhen the winding is deenergized or its energization reduced to a predetermined minimum, the plunger 74 falls, and the head 10, striking the finger 11, opens the switch contacts, and also returns the armature 79 to its normal position shown.

In the form of my invention shown in Fig. 4, the magnetic circuit energized by the winding 80 has the main 81, the stationary pole piece 82 supported in the main frame by the shoulder 83, the vertically movable plunger 84, and the vertically movable auxiliary plunger 85 preferably enlarged at its lower end to increase its weight. Two gaps are provided, the gap 86 between the pole piece 82 and the plunger 84, and the preferably larger gap 87 between the plunger 84 and the auxiliary plunger 85. The plunger 84 is suspended in position by the non-magnetic tubular stem 88, threaded into the plunger 89, and passing upwardly through the pole piece 82, and having the head 90 resting on the pole piece. The head 90 continues upwardly, passing between the legs 92 (only one of -which is shown) of the fork on the finger finger 56, adapted to engage the legs 92 of the fork. The vertical movements of the plunger 84 cause these shoulders to lower or, raise the finger 56; The auxiliary plunger 85 is suspended in position by the brackets 91 engaging the annular shoulder 86 on the plunger. The non-magnetic stem 97 passes through and is vertically .movable in the head 90, the tubular stem 88, the plunger 84, and the auxiliary plunger 85., and isnormally suspended in position by the collar 98 on the stem, the collar resting upon the upper end of the auxiliary plunger 85. Another collar 99 on the stem 97 isnormally spaced from'the lower end of the auxiliary plunger 85, as shown at 100, and another collar 101 on this stem is normally spaced from the upper end 102 of the head 90,

When the winding is energized, the flux fiows, say, upwardly, in the plunger 84, across the gap 86, into the pole piece 82, through the main frame 81 to the lower part thereof, and upwardly through the auxiliary plunger '85 and the gap 87 to the plunger 84. nder certain conditions of current in the winding, to be described, either the plunger 84 or both this plunger and the auxiliary plunger 85 are lifted and control the operation of the switch members, which will now be described.

The switch arm 94 and the contact members actuated thereby-are the same in all essentials as those shown in connection with the switch arm 57 of Fig. 2, with the fol lowing exception: The switch arm 94, be-

sides having the normally horizontal finger 56, has another normally horizontal finger 103.. A perforation 104 in the finger 103 is located immediately above the upper end' of the stem 97, so that, when the switch arm 94 is in the normal open position shown, a

vertical movement of the stem 97 will carry its upper end into the perforation.

The operation of the form of my invention shown in Fig. 4 is as follows: When the winding 80 is energized with current belowa predetermined value, the magnetic pull in the gap 86 lifts the plunger 84, closing the gap 86 and carrying the stem 88 and the head .90 upwardly. The shoulder 96 strikes the finger 56 and rotates the arm 94 counterclockwise until the line of action of the spring 60 lies below the center of the pivot 58, whereupon the spring continues to rotate the arm 94 counterclockwise, closing the switch contacts as described in connectionwith Fig. 2. This movement of the arm 94 rotates the perforation 104 of the finger 103 to the left, and out of the path of the vertically movable stem 97. The continued upward movement of the plunger 84 and the head-90 causes the upper end 102 of the headto engage the collar 101, thereby lifting the stem 97 and with it the collar 99.

'which closes-up the space 100 and finally weighted auxiliary plunger 85, which in turn lifts the collar 98 and the stem 97, so that when the plunger 84 moves upwardly, the plunger 85 and the stem 97 move wit-h it, the plungers being spaced a constant distance apart by the collar 98. At the first upward movement of the parts, the upper end of the stem 97 enters. the perforation 104 in the finger 108. l/Vhen thereafter the shoulder 96 engages the finger 56 to rotate it counterclockwise, the perforation 104 will tend to rotate to the left, but the right-hand inner wall of the perforation will engage the stem 97 and rotation will be prevented, and the switch will not close, this condition continuing so long as the auxiliary plunger 85 is held up. When the current is reduced to or below the predetermined value, the pull in the gap 87 becomes insufficient to hold the plunger 85, and it falls, first falling freely to closeup the space 100, and then giving a hammer blow to the collar 99, which erks the stem 97 downwardly out of the per- 7 foration 1 04. The switch arm 94 now beingfree to rotate, the flux in the gap 86 continues the upward movement of the plunger 84, and the shoulder 96'on the head 90 causes the switch to be closed as described. The further upward movement of the plunger 84, during the closure of the gap 86, again lifts the auxiliary plunger 85 by means of the collar 99, as before described, and holds both plungers up so long as the winding is energized.

As is well known, switches having the general operating characteristics described herein may be used for controlling the starting resistance of an electric motor, and it is, therefore, not deemed necessary toshow herein an application of my invention to practical uses. It is apparent that the switches herein described may be substituted for the accelerating switches shown in many motor control systems. For example, my switches may be readily substituted for the accelerating switches shown in my application, Serial Number 583,000, or in Halls Patent Number 1,197,584.

My invention is not limited in its application to motor control or motor-starting purposes. Many changes and modifications other than those shown may be made without departing from the spirit of my invention; for example, I have shown four forms of magnetic circuit by which the desired characteristics are developed in response to current conditions in the winding, and it will be apparent that other forms of magnetic circuit may be employed. WVhile I have shown the mechanical bias which holds the switch contacts open and the mechanical bias which holds them closed as produced by a compression spring acting on alternate sides of center of rotation, it will be apparent that other means employing either springs or gravity, or their equivalent, acting without the necessity of magnetic assistance from the winding, may be employed. Other changes and modifications may be made.

I claim 1. A controlling device for electric circuits containing a winding, a movable switch member, means for biasing the same toward open and closed position from an intermediate position, and means influenced by the current in the winding when below a predetermined value for moving the movable member to such a position in the closing direction that the biasing means may complete the closing movement of the movable member, and when the current is at or above the said value, for preventing the movement of the said member.

2. A controlling device for electric circuits comprising a winding, a movable switch member, means for mechanically biasing the same to both the closed and open positions, and means whereby the bias to open position is overcome and the switch member closed by its closing bias when the winding is energized with current below a predetermined value, and whereby the bias to open position remains when the current is at or above the said value.

3. A controlling device for electric cir cuits comprising a winding, a movable switch member, means for mechanically biasing the same to closed position, and means whereby, when the winding is energized with current below a predetermined value only, the switch arm is moved by its bias to closed position, and whereby the switch member remains in closed position when the winding is energized with current above a predetermined minimum.

i. A controlling device for electric circuits comprising a winding, a movable switch member, mechanical means whereby the switch member is moved to closed position, and means whereby the switch member remains in open position irrespective of the magnetism produced by the winding when the current in the winding is above a predetermined value, whereby the switch member is caused to be moved to closed position when the winding is energized with current below the predetermined value, and whereby the switch member remains in closed position when the current in the winding is above a predetermined minimum.

Signed at Cleveland, Ohio, this 13th day of February, A. D. 1917.

HARRY R. CANFIELD. 

